A multiple-input switched-capacitor DC-DC converter which can realize long battery runtime is proposed in this letter. Unlike conventional converters for a back-lighting application, the proposed converter drives some LEDs by converting energy from solar cells. Furthermore, the proposed converter can charge a lithium battery when an output load is light. The validity of circuit design is confirmed by theoretical analyses, simulations, and experiments.

In this paper, we propose a voltage controlled oscillator (VCO) with up mode type Miller-integrator. The controlled voltage of this VCO can continuously change 0 V center in the positive and negative bidirection. Also, the relationship between control voltage and oscillating frequency shows the good linearity, and the calculated and the measured values agree well.

In this letter, we propose a simple voltage controlled oscillator (VCO) with circuitry combining a Miller integrator and an RS flip-flop circuit. With the VCO, the control voltage can be varied over a broad range, and the oscillation frequency varies in proportion to the control voltage. The maximum voltage is up to 1000 times the minimum, and the calculated design values and measured values agree well. This VCO can be applied to FM modulators, FSK modulators, and other systems.

This paper proposes a new all digital dividing ratio changeable phase locked loop (D-DCPLL) using delay clock pulse that exhibits low output jitter characteristics compared with the conventional DCPLL. This is achieved by employing the delay clock pulse generated from the ring oscillator for the standard clock controlling the loop. This output jitter is always constant regardless of the frequency fluctuation of the delay clock, and the fluctuation coefficient has little effect on the output jitter. This circuit can expand the upper bound frequency of the lock-in range compared with conventional DCPLL when the permissible output jitter is identical. Furthermore, the proposed D-DCPLL can obtain an initial pull-in in one period of the input signal and the multiplication output signal of the constant pulse interval can be obtained by using the remainder control circuit.

This paper explores the potential of orbital angular momentum (OAM) multiplexing as a means to enable high-speed wireless transmission. OAM is a physical property of electro-magnetic waves that are characterized by a helical phase front in the propagation direction. Since the characteristic can be used to create multiple orthogonal channels, wireless transmission using OAM can enhance the wireless transmission rate. Comparisons with other wireless transmission technologies clarify that OAM multiplexing is particularly promising for point-to-point wireless transmission. We also clarify three major issues in OAM multiplexing: beam divergence, mode-dependent performance degradation, and reception (Rx) signal-to-noise-ratio (SNR) reduction. To mitigate mode-dependent performance degradation we first present a simple but practical Rx antenna design method. Exploiting the fact that there are specific location sets with phase differences of 90 or 180 degrees, the method allows each OAM mode to be received at its high SNR region. We also introduce two methods to address the Rx SNR reduction issue by exploiting the property of a Gaussian beam generated by multiple uniform circular arrays and by using a dielectric lens antenna. We confirm the feasibility of OAM multiplexing in a proof of concept experiment at 5.2 GHz. The effectiveness of the proposed Rx antenna design method is validated by computer simulations that use experimentally measured values. The two new Rx SNR enhancement methods are validated by computer simulations using wireless transmission at 60 GHz.